The steam engine was the first effective machine for producing power independently of human and animal muscle, wind, or flowing water. Its invention and application in the early 18th century was one of the technological foundations for the industrial revolution. There are two fundamental forms of steam engine, reciprocating and turbine. The latter, which supplies the vast bulk of power for modern electrical generation, is generally called a steam turbine. The reciprocating engine is the classic form of the steam engine, whose elaboration and refinement was one of the great triumphs of 18th- and 19th-century science and technology. The challenges of improving the steam engine, in fact, gave birth in the 19th century to the science of thermodynamics.